Today's been a day when I've done a lot of thinking about maps.
It started when I went into Julian Graves to get myself some cashew nuts. They've just taken delivery of a new map of Norwich - a rather nice map, the kind that is illustrated with little pictures of the buildings. I was quite impressed. It was free, which is even more impressive.
Then someone mentioned to me the maps of John Rocque, an eighteenth century mapmaker who worked in London. I remember Rocque's name - there was a very good brasserie near Liverpool Street Station that bore his name, and was illustrated with fine enlargements of his maps. (Wonder if it's still there.) It's fascinating looking at his maps because they give you a feeling for the density and patterning of the city of his day - the small courtyards that open up in the middle of thick dark blocks of building, the way the whole riverbank of the City was carved up by long, narrow alleys just like Lowestoft's scores or Yarmouth's rows, giving access to the wharves.
A lot of that has changed - but not by any means all of it. Some patterns continue but in a slightly different form. The wide expanse of Farringdon Road now divides the City from Fleet Street - a great traffic artery where Rocque shows the Fleet Ditch. (If you look at the map with your eyes half closed, the two-banks-and-river format looks almost like a three lane motorway.)
And some things stay just the same. Right in the centre of his London map is the bulky shape of St Paul's with its crowning dome. That hasn't changed a bit.
Rocque's plans are what we expect of a map nowadays - though he does try to show the internal arrangements of the major churches, too, so you can see the nave, aisles and chapels at Westminster Abbey. But John Speed, making his maps in sixteenth century England, shows the cities more like the Norwich map I got today, with pictures of the buildings' elevations.
What's really stunning in all these old maps is to see how rural England still was. King's Road Chelsea, on Rocque's map, is a long, winding country road with not a house along its length. Pimlico is just orchards.
A map isn't just an archaeological record of course. It's a way that we try to categorise and organise our experience. And we have different ways of using them. When I'm hiking, my map serves for navigating on the ground. But I also have an overall map of the long distance path - and every evening, before I go to bed, I colour in the bit I've done today. It's a moment I've waited for, and I really savour it. It encapsulates my satisfaction with what I've done. And it gives me anticipation for what's still to come.
When I walked to Santiago, I drew the landscape another way, too. I transferred the contours from the map to a chart of the elevation, so I could see 'how high am I today'? Usually, a chart like this flattens out the terrain - but I was impressed to see just how big the mountain pass of O Cerbreiro still looked when I'd charted it.
And now we have Google Maps and some fascinating mashups which merge other data with mapping. Whether you want to see crime rates in New York, or your address book as a map, Google has opened up new ways for us to chart our experience of the world around us.